Stringed musical instrument



March 15, 1938. c. w. RUSSELL 2,111,334

STRINGED MUSICAL INSTRUMENT Filed July 1, 1935 2 Sheets-Sheet l n1III-IIIII-III l nllllllllll I lnvcnlor C. W. Russell pmm A Home};

March 15, 1938. c. w. RUSSELL STRINGED MUSICAL INSTRUMENT Filed July 1,1935 2 Sheets-Sheet 2 C. W. Russell Patented Mar. 15, 1938 STRINGEDMUSICAL INSTRUMENT Clarence W. Russell, Longton, Kans., assignor ofone-hall. to Duane Prather, Longton, Kans.

Application July 1, 1935, Serial No. 29,325

3 Claims.

My invention relates generally to means for producing and transmittingto a remote point vibrations corresponding to musical tones, andparticularly to a stringed musical instrument which is operativelyconnected to electrical amplifying and recording means whereby soundsengendered by playing upon the strings thereof may be transmitted andamplified with perfect naturalness.

Another important object of my invention is to provide an instrument ofthe character indicated above which is not subject to the production ofvarying and distorted tones because of vibra-" tions of the strings indifferent and divers directions, and in which all restrictions to thenatural and full vibration of the strings are eliminated and the fullvalue of the vibrations electrically transmitted.

Another important object of my invention is to provide means of thecharacter indicated above which does not utilize any sound box and isdevoid of the conventional sound opening. I

Another important object of my invention is to provide an instrument ofthe character indicated above which includes electrical means inmagnetic relation to the magnetically permeable strings of theinstrument, which is effective for transmitting the vibrationsunimpaired for reproduction and amplification, notwithstanding vibrationof the strings in different directions and at different frequencies.

Another important object of my invention is to provide in an arrangementof the character indicated above electrical means whereby the frequencyvibrations of the strings are perfectly electrically transformed into acorrespondingly alternating current of the same frequency orfrequencies, whereby reproduction of the sounds in an electrical manneris perfectly achieved with the same volume, notwithstanding the factthat the string or strings may be vibrating in different and diversdirections.

Other important objects of my invention will be apparent from a readingof the following de- Figure 4 is an end elevational view taken from thebottom of Figure 3 and looking upwardly.

Figure 5 is a transverse vertical sectional view taken through Figure 3approximately on the line 5-5 and looking upwardly in the direction ofthe arrows.

Figure 6 is an elevational view looking from right to left in Figure 3.I

Referring in detail to the drawings, the numeral 5 generally designatesthe hollow instrument body 6 which may be in the form of a guitar havingthe neck I and the nut Ill thereon.

' The magnetically permeable strings 9 preferably of steel are stretchedbetween the nut I0 and the tail piece l2 over the bridge H which restson the top 6' of the instrument. It is to be noted that the top of theinstrument is devoid ofa sound hole as is present in conventionalinstruments of this general type.

At one side of the strings the top 6' is provided with a potentiometerswitch handle [3 for controlling a resistance in the wires I! whichconnect with the inductive winding of the pickup unit I 6 andwith thejack l4 which is mounted in a side wall of one end of the body of theinstrument and has extending therefrom the wires I6 which lead to asuitable sound reproducing and recording and amplifying device (notshown) The pick-up unit 16 is mounted in an accommodating opening in thetop 6' between the bridge H and that part of the strings which have thegreatest amplitude of vibration and which lie between the finger boardand the bridge.

The pick-up unit 16 comprises the rectangular frame, which includes therectangular elongated magnetically permeable bar I8 from whose left endrises the vertical magnetically permeable rectangular cross-section barl9 and from whose right end rises a vertical non-magnetic rectangularcross section bar 20. Screws 22 mount the vertical members l9 and 20 onthe base 18. The top piece 2| is also a rectangular elongatedmagnetically permeable bar and is secured to the tops of the verticalmembers l9 and 20 by screws 22, thereby forming a permanent magnet of U-shaped form. The bars l8, l9 and 2| form a U- shaped permanent magnetsupported at its open end by the vertical non-magnetic rectangular crosssection bar 20. It will be evident from Figures 4 and 5 that thevertical members i9 and 20 are angulated with respect to theperpendicular and with respect to the base I8 and the top member 2|, sothat the member 2| is displaced toward the keyboard with respect to theperpendicular toward the right in Figures 1, 2, 8, 4 and 5.

The member ii of magnetically permeable metal has depending therefrom anumber of lugs a corresponding in number and position to the strings I,and each lug is provided with a horizontal opening 21 receiving thecorresponding string and of a diameter sufficient to permit full andunobstructed vibration of the string I.

To the left of the lugs it are magnetically permeable risers 80 whichare magnetically connected to the base It and which correspond in numberand are vertically aligned with the lugs 2!. Each riser ll has on itsupper end a vertically projecting lug it which is provided with ahorizontal opening it therein which corresponds in size and in axialalignment with the openings 21inthehigs2|,andthestringslpassalsothroushtheopeningsllofthelugsll.

Wound horiaontally around the risers II are turns of relatively nne wirewhich form the coil 82 which is in inductive relation to the permanentmagnet by this arrangement and has its opposite ends connected to thereproducing and amplifying unit by the wires i'i already described.

Each vertical side member II, It has a respective ear II, 24 which has ascrew receiving opening 2! to receive a bolt or screw for attaching thereproduction unit to the top I of the instrument.

overlying and extending from all sides of the lugallistheheadliwhichconilnesthecoilfl in place.

Bythe arrangementdescribedthetopmember Ii becomes the south pole of apermanent magnet while' the base il becomes the north pole thereof. Thecoil 82 being in inductive relation to this permanent magnet. there isinduced in the coil 32 by the vibration of the strings O variations inthe magnetic field which correspond exactly in frequency to thevibrations of the strings and the amplitude thereof. so as to producealternating current in the wires I! which leadto the reproducing andamplifying device which may be of any suitable conventional type. v

The strings f are conventionally arrang with the base or lowestfrequency vibration string uppermost as shown in Figure 2 and thehighest frequency string lowermost. The magnet exerts its greatest forceat the open end thereof whereat the non-magnetizable member II islocated and consequently the apertured elements immediately surroundingthe lowest vibration frequency string exert the strongest inductiveefl'ect. The next pair of apertured elements surrounding the next higherfrequency string exert a smaller magnetic action and, therefore, thisnext higher frequency string exerts by its vibration a smaller inductiveeffect. The apertured elements surrounding the highest frequency stringbeing farthest from the strong end of the magnet exert the smallestinductive effect upon the coil I! of any of the strings. By means ofthis arrangement, the recording device is caused to reproduce the soundsof the different strings in substantially the same volume,notwithstanding the fact that the dinerent strings mechanically vibrateat different frequencies. In this way is overcome the serious defect ofother arrangements of this general character in failing to reproducewith suitable equality of volume the sounds and tones which have theirorigin in mechanical elements producing them by vibrating at differentfrequencies.

It will also be evident that by the described arrangements equal volumeis produced from each individual string regardless of the diiferent anddivers directions in which the strings are made to vibrate.

Although I have shown and described herein a preferred embodiment of myinvention, it is to be definitely understood that I do not desire tolimit the application of the invention thereto. and any change orchanges may be made in the materials, and in the structure andarrangement of the parts, within the spirit of the invention and thescope of the subioined claims.

What is claimed is:-

1. A musical instrument of the character described comprising a bodyportion including magnetically permeable strings of progressivelydifferent vibration frequencies stretched thereacross. anelectro-magnetic pick-up unit mounted on said body and including apermanent magnet having portions of opposite magnetic polarity spacedlongitudinally along each string and in effective magnetic relationthereto, said magnet having coil means thereon whereby alternatingcurrentsareproducedinsaidcoilmeans correspondinginfrequencytothefrequencyof the vibrations of the respective strings when the stringsare played upon. the magnetically strongest of said portions of saidmagnet being arranged in effective magnetic relation to the lowestfrequency string and progressively less magnetically strong portions ofsaid magnet being arranged in effective magnetic relation progressivelyrelative to the lower frequency strings, said permanent magnetcomprising an upper arm lyingaboveandacrosssaidstringaalowerarmofopposite polarity lying below said strings, each of said arms having alug connected thereto and extending therefrom and formed with an openingreceiving and having its sides spaced from the correspondingindividualstring. a magnetically permeable member connecting said armsat one end only,saidcoilmeansbeingwoundon magnetically permeable membersprojecting from one of said arms.

2.A musical instrument comprising a body having magnetically permeablestrings stretched thereacross, said strings having different mechanicalvibration frequencies. an electrical pickup unit mounted on said body,said pick-up unit comprising a permanent magnet having coil means woundon a part thereof. said permanent magnet havinganupperarmiyingacross andspacedabovesaidstringaalowerarmlying across and spaced below saidstrings. said arms being of opposite magnetic polarity, and a yokeJoining the upper and lower arms at one end thereof, said arms eachhaving a magnetized portion surrounding and concentrically spaced fromeach string in effective magnetic relation thereto, the said magnetizedportions being distributed along said arms so that the magnetizedportions surrounding the strings of weaker vibration will exert greatermagnetic force thereon and the magnetlsed portions surrounding the morestrongly vibrating strings will exert less magnetic force, whereby theelectro-magnet effect of the vibrations of the different strings isequalized. and alternating currents of equal value are set up in saidcoil means for actuation of a reproduction unit regardless of thestrings P yed upon and regardless of the different directions in whichthe individual strings are made to vibrate.

3. A musical instrument comprising a body having magnetically permeablestrings stretched thereacross, said strings having diflermt mechanicalvibration frequencim, an electricalpickupunitmountedonsaidbodamididebupunit comprising a permanent magnethaving coil means wound on a part thereof, said permanent magnet havingan upper arm lying across and spaced above said strings, a lower armlying across and spaced below said strings, said arms being of oppositemagnetic polarity, and a yoke joining the upper and lower arms at oneend thereof, said arms each having a magnetized portion surrounding andconcentrically spaced from each string in effective magnetic relationthereto, the said magnetized portions being distributed along said armsso that the magnetized portions surrounding the strings of weakervibration will exert greater magnetic force thereon and the magnetizedportions surrounding the more strongly vibrating strings will exert lessmagnetic force, whereby the electro-magnet effect of the vibrations ofthe different strings is equalized, and alternating currents of equalvalue are set up in said coil means for actuation of a reproduction unitregardless of the strings played upon and regardless of the differentdirections in which the individual strings are made to vibrate, saidmagnetized portions each comprising a 'ug projecting from thecorresponding arm of the permanent magnet and formed with a bore havingits axis parallel to that of the corresponding string, the lugs for eachstring being axially spaced along the strings.

CLARENCE W. RUSSELL.

